Ultra Wideband Impulse Radio (UWB-IR) is an emerging next generation worldwide technology for short range radar and wireless communications. UWB-IR utilizes extremely short pulses (picosecond/sub-picosecond) to transmit information rather than transmitting information employing the traditional sinusoidal carrier. Filters are then employed to match the spectrum mask. UWB-IR possesses fine multi-path resolution with great potential to solve difficult mobile or indoor communications problems, such as fading, interference, etc. UWB-IR is a spread spectrum signaling technology that occupies a large bandwidth with low transmitting power spectral density, and can co-exist with other systems. A UWB-IR modulator can be built utilizing a simple system configuration eliminating the need for an up/down converter and frequency recovery loops.
UWB-IR modulators have been built employing different types of technologies. For example, J Wang et al. discloses a UWB-IR modulator that generates a picosecond pulses by employing a high speed RF switch in an article entitled “A Modulation Circuit for Impulse Radio Ultra-Wideband Communications” in the Proceedings of the 2005 Asia-Pacific Microwave Conference. However, the switch speed limits the bandwidth of the baseband signal and may introduce undesired waveform distortion. Additionally, the modulator employs a step recovery diode (SRD) for pulse generation. Step Recovery Diodes (SRDs) have potential instability and repeatability issues. Y Kawano et al. discloses a pulse generator for generating picosecond pulses that are biphase modulated by employing a digital IC techniques with a delay control buffer and an AND circuit in an article entitled “Sub-10 ps Pulse Generator with Biphase Modulation Function in 0.13 um InP HEMT” also in the Proceedings of the 36th European Microwave Conference. The digital IC technique can consume amounts of power (approximately 640 milliwatts) that are unacceptable for certain applications.